The conversion of fuels into electricity has long been the focus of engineers. The supply of the fuel to a generation site, as well as the reliability and cost of the supply, is factored into the engineering decision process.
The thrust of waste heat recovery technology is to make use of thermal energy normally discarded from a primary power conversion process. In many prior art devices, the discarded thermal energy (i.e., waste heat) is harnessed to drive additional thermo-fluid processes that can yield additional energy (i.e., electricity).
Referring to prior art FIG. 1, the prior art waste heat recovery system directs a supply of waste heat measured at temperatures between 300° F. to 800° F. from a heat source to an evaporator (see numeral 1). The waste heat is transferred to a working fluid in the evaporator. The working fluid is evaporated; changes from a liquid to a vapor, in the evaporator and is expanded through a turbine (see numeral 2). The expansion of the working fluid through the turbine drives the turbine. The turbine, in turn, drives an electric generator coupled to the turbine. The generator produces electrical power. The working fluid flows to a condenser and changes phase from vapor to a liquid (see numeral 3). The liquid working fluid is then pumped back to the evaporator and begins the cycle again (see numeral 4). The above described system employs a closed-loop Organic Rankine Cycle to produce electricity from a thermal energy source, such as waste heat. This example illustrates that the prior art waste heat recovery systems were utilized to produce electricity.
Using the above concept of a reverse refrigeration cycle, either a Rankine Cycle or Organic Rankine Cycle (ORC), the waste heat of an engine can be converted to produce a more efficient engine; not electricity. However, the above example relies on turbines to operate the generator. Turbines operate at a greater rotational speed than conventional engines and require extensive, complex machinery in order to try and capture the thermal energy for reuse as mechanical energy.
What is needed in the art is a Rankine Cycle or an Organic Rankine Cycle system to convert waste heat from an engine into useful power for the engine that is simple, reliable and cost effective.